1. Technical Field of the Invention
The present invention relates to an electric-wire holding structure which is formed in a wiring board for forming predetermined circuits inside a connector housing or an electrical connection box used in the electrical connection of a wire harness in a vehicle such as an automobile, and more particularly to an electric-wire holding structure having wire clamping portions capable of speedily and reliably clamping various electric wires of different wire diameters.
2. Related Art
In a vehicle such as an automobile in which various electronic apparatuses are mounted, a large number of connectors are used for electrical connection between the respective electronic apparatuses or between each wire harness and the electronic apparatuses. As a related connector, one disclosed in, for example, JP-A-2-295074 or the like is known. As shown in FIGS. 8 and 9, a connector 10 is known in which an electric wire 1 having a covering 2 is inserted and fitted in a plate-like housing 11 in which a wire accommodating slot 12, a wire cutting blade 13, a pair of covering cutting-in blade 14, and a pair of wire clamping pieces 16, which are linearly arranged in order, are integrally molded.
With the above-described connector 10, with the exception of the metallic wire cutting blade 13 which is insert-molded for cutting an end portion of the wire 1, the pair of covering cutting-in blades 14 made of a metal are formed by bending as single pieces separately from the plate-like housing 11. The covering cutting-in blades 14 are provided with the so-called function of an insulation displacement terminal, and are adapted to cut the covering 2 of the wire 1, which is press-fitted between the opposing portions of a substantially U-shaped gap portion, by their edge portions, and are thereby brought into contact with a core so as to obtain a conducting state.
In addition, the flexural rigidity of the wire clamping pieces 16 toward the covering cutting-in blades 14 is weakened by a pair of vertical slots 15 each provided between the wire clamping piece 16 and the covering cutting-in blade 14, a pair of undercut portions 18 provided so as to separate the wire clamping portions 16 from a bottom 12a of the wire accommodating slot, and a pair of chamfered portions 19 for forming an inverse V-shaped opposing gap 17. When the wire 1 is press-fitted in the opposing gap 17, the wire clamping pieces 16 are resiliently displaced toward the covering cutting-in blades 14 while displacing the covering 2 and clamping the outer surface of the covering.
In addition, the displacement of the wire clamping pieces 16 in an opposite direction to the direction toward the covering cutting-in blades 14 is suppressed, thereby preventing the wire 1 from coming off in its axial direction. Further, the coming off of the wire 1 in the upward direction is prevented by the inverse V-shaped opposing gap 17 between the pair of wire clamping pieces 16.
However, the above-described related connector 10 has a drawback in that the force with which the wire 1 is clamped is likely to deteriorate with a decline in the flexural rigidity of the wire clamping pieces 16 in the plate-like housing 11 due to the vertical slots 15, the undercut portions 18, and the chamfered portions 19.
In addition, because the wire 1 is clamped by one pair of wire clamping pieces 16, in a case where the wire diameters are of various types, it is impossible to cope with the various wire diameters since the opposing gap 17 between the wire clamping pieces 16 is fixed. Hence, there has been a problem in that exclusive-use plate-housings 11 are required for the respective kinds of wires.
The invention is aimed at overcoming the above-described problems of the conventional art, and its object is to provide an electric-wire holding structure which is capable of speedily and reliably clamping electric wires having various diameters over a relatively wide range.
In accordance with the invention, the above-described problems can be solved by an electric-wire holding structure including:
a wire accommodating slot for linearly wiring a covered wire; and
a pair of first wire clamping pieces and a pair of second wire claming pieces, each of which are disposed at the wire accommodating slot and are opposed each other with respect to the wire accommodating slot for holing the covered wire;
wherein a center line between the pair of first wire clamping pieces is offset in one direction from a center line between the pair of second wire clamping pieces, and
wherein a shortest interval connecting an inner end corner of the first wire clamping piece and an inner end corner of the second wire clamping piece is set to be equal to an opposing interval between the pair of first wire clamping pieces and an opposing interval between the pair of second wire clamping pieces.
In addition, preferably, to solve the above-described problems, wire clamping portions respectively including the pair of first wire clamping portion and the pair of second clamping portion are separately provided at the wire accommodating slot as a large-size wire clamping portion for large-size wire and as a small-size wire clamping portion for a small-size wire in correspondence with outside diameter of the covered wire.
Further, preferably, the electric-wire holding structure according to claim 1 further comprises an insulation displacement terminal for press-fitting the covered wire provided at the wire accommodating slot.
Further, preferably, opposing end faces of the pair of first wire cramping pieces are substantially parallel each other.
In accordance with the above-described electric-wire holding structure, the opposing interval between the pair of first wire clamping pieces in the wire accommodating slot and the opposing interval between the pair of second wire clamping pieces located adjacent to the pair of first wire clamping pieces are set to be equal, and the center line between the pair of second wire clamping pieces is offset in one direction from the center line between the pair of second wire clamping pieces. In addition, the shortest interval connecting an inner end corner of the first wire clamping piece and an inner end corner of the second wire clamping piece is set to be equal to the opposing interval between the pair of first wire clamping pieces and the opposing interval between the pair of second wire clamping pieces.
Accordingly, as the wire is inserted between the pairs of first and second wire clamping pieces, the wire can be held by the inner end corner of the first wire clamping piece and the inner end corner of the second wire clamping piece as well. Hence, the wire can be clamped in a meandering state at three positions between the pair of first wire clamping pieces, between the pair of second wire clamping pieces, and between the inner end corners of the first and second wire clamping pieces. Accordingly, electric wires having various wires diameters over a relatively wide range can be held speedily and reliably, and it is possible to reliably prevent the wire from coming off in the axial and upward directions.
In addition, in the above-described electric-wire holding structure, since the pair of large-size wire clamping portions and the pair of small-size wire clamping portions are provided in the same wire accommodating slot in correspondence with outside diameters of the covered wires, it is possible to apply the electric-wire holding structure to electric wires having at least two kinds of wire diameter, and an appropriate meandering state can be formed inside either wire clamping portions depending on the wire diameter. Accordingly, the electric wires of various diameters can be clamped more reliably between the wire clamping pieces.